In food processor combine tomatoes, cilantro, onions, garlic, salt, & vinegar pulse until mixed together.Put this mixture plus lime juice in slow cooker, then put meat on top.Mix meat around to coat it, then add beef broth.Put the bay leaves on top of meat.I cooked on low starting around 9pm, then turned on warm @ 6am (just happened to wake up) I left it on warm until 8am.I then shredded the meat & disposed of the bay leaves.I returned the shredded meat to the crock pot & removed the extra broth that was around it.(You want it to sit in the broth not swim in it.You also can freeze this leftover broth for next time or other dishes!) I then left it on warm to absorb the juices until 5pm when we had dinner.